Socket for plug fuses



April 14 19365 J. v, CUNNINGHAM 2,637,120

SOCKET FOR PLUG FUSES Filed Feb. 5, 1954 Patented Apr. 14, 1936 UNITEDSTATES PATENT OFFICE SOCKET FOR PLUG FUSES James Vernon Cunningham, St.John, New Brunswick, Canada 1 Claim.

This invention relates to improvements in sockets for plug fuses, andthe objects of the invention are to limit the size of fuse which may beused with a given socket thereby preventing the over-fusing of branchcircuits beyond the established limits, and to prevent the improper useof substitutes such as copper cents for the plug fuses. It consistsessentially of a socket having a central contact on the base thereofwith an insulating partition in advance of the contact having arestricted aperture therein designed to fit closely to the centralcontact of a plug fuse of given size, the arrangement being such thateach size of a plug fuse will have an appropriate sized aperture in theinsulating partition as hereinafter more fully set forth and describedin the accompanying specification and drawing.

In the drawing Fig. 1 is a sectional elevation of a socket embodying thepresent invention.

Figs. 2 and 3 are front elevations showing sockets for two differentsizes of plug fuses.

Figs. 4 and. 5 are side elevations of two different sizes of plug fusedesigned to fit into the sockets shown in Figs. 2 and 3.

In the drawing like characters of reference indicate corresponding partsin all the figures.

Referring to the drawing, A represents a fuse plug socket having acylindrical shell 9, said socket being preferably screw-threaded at Illto receive the plug, and being formed at the base with a central contactI I insulated from the socket, this contact being connected to anelectrical conductor l2, the other electrical contacts for the socketnot being shown and not relating to the present invention.

According to the present invention there is provided in the socket A inadvance of the contact II and spaced therefrom an insulating partitionor washer I 3 of fibre or other convenient insulating material,supported in position by small screws I4 and I5 which may extend intothe base I! formed of insulating material in which the socket A is set.When in place insulating partition I3 retains the cylinder shell 9 inits proper position since it rests on a turned in flange It at the innerend of said shell, as shown in Figure 1. The partition I3 is supported ashort distance in advance of the base and is formed with a restrictedaperture I6 in its center, preferably circular, immediately in front ofthe contact I I and designed to receive the central contact I8 of thefuse plug which should be of a special size and shape to fit closely tothe aperture. The size of the apertures in each socket will correspondwith the plug which it is designed to receive. For instance the socketshown in Fig. 2 has an aperture of a smaller size than that shown inFig. 3, and might be designed to receive contacts from plugs up to 15amperes, while the larger aperture shown in Fig. 3 might receivecontacts from plugs of 30 ampere capacity.

Figs. 4. and 5 show the plugs C corresponding to the sockets in Figs. 2and 3. The construction of the fuse plugs themselves does not form partof the present invention. As far as the present invention is concernedit is only necessary that the central contact IS on the plug should beof a size closely to fit the aperture in the insulating washer I3 of thesocket which it is designed to fit. The plug for instance shown in Fig.4 is designed to fit the aperture in the socket shown in Fig. 2, whilethat shown in Fig. 5 fits the aperture shown in Fig. 3.

With the arrangement described it will be possible to avoid theover-fusing of branch circuits beyond the limits set by the standardcode, since the sockets for the lower capacity fuse plugs will notreceive larger capacity fuse plugs, and further it will not be possibleto use copper cents or other expedients in place of the fuse plugs,since the insulating washer will prevent their making the propercontact. The result will be a substantial reduction in fire loss, and asthe consumers of an electrical system will not be able to overload theirbranch circuits they will be able to get better lighting and a moreadvantageous use of their various appliances.

Various modifications may be made in the invention without departingfrom the spirit thereof or the scope of the claim and, therefore, theexact forms shown are to be taken as illustrative only and not in alimiting sense, and I desire that only such limitations shall be placedthereon as are imposed by the prior art or are specifically set forth inthe appended claim.

What I claim as my invention is:

A fuse plug socket having a cylindrical shell with 2. turned in flangeat its inner end, said socket having a central contact at the basethereof and a partition formed of insulating material secured in advanceof the contact and resting on the flange, said partition being adaptedto hold said cylindrical shell in place and having a restricted aperturethrough which a contact on a fuse plug of given size may pass.

JAMES VERNON CUNNINGHAM.

Jill

